Approximately ten years ago, United States vehicle manufacturers began using all foam seat pads to replace the cloth pads, burlap, and cloth ticking, etc. previously utilized. Introduction of the foam seat pads provided cost reduction, reduced the number of components that had to be inventoried, and facilitated assembly of the seats. Conventionally, such foam seat pads have been mounted on a frame pan stamped from sheet metal with the required shape for supporting the pad. Such sheet metal pans are continuous over the extent of the foam pads and despite the relatively thin thickness thereof have considerable weight when taking into account the total number of seats in each vehicle. Of course, with the ever-increasing scarcity of available fossil fuels for powering conventional vehicle engines, weight reduction of vehicles is highly desirable.
Torsion bar type wire springs have previously been considered for supporting foam seat pads so as to, among other things, reduce the weight of the seat in comparison to those incorporating the stamped pans. These springs are either of the "sinuous" type wherein torsion bars thereof are connected by curved connecting loops that open in opposite directions or are of the "formed wire" type wherein the ends of the torsion bars are connected by abrupt bends to straight connecting portions so as to define either U or Z shapes. However, such springs have to be individually handled for assembly and can become entangled with each other prior to assembly so as to present a manufacturing problem. Also, if the ends of such springs are to be directly connected to an associated metal seat frame, noise problems can result from the metal-to-metal contact between the springs and the frame. To overcome these problems, consideration has previously been given to connecting the ends of torsion bar springs to paper or plastic covered wires which extend transversely between the springs and are in turn connected to the seat frame. However, such transverse wires limit the independent resilient action of the individual springs. Additionally, the extra weight of the transverse wires as well as the necessity of connecting each spring end thereto as well as connecting the transverse wires to the frame resulted in too many undesirable features to make a commercially feasible product.
Furthermore, consideration has also been given to interconnecting closely spaced wires by paper or plastic covered wire to essentially form a wire mat for supporting a foam seat pad. However, such a construction does not provide the proper feel to a seated occupant and thus has never become a commercial product.